Spike Chunsoft’s popular visual novel 999: Nine Hours, Nine Persons, Nine Doors has recently been released for iOS in Japan. Atlus USA just announced that they will be localizing this version and bringing it to the US.
One of the main differences between this version and the original DS game is that the puzzles have been removed- so this version is just a straight up visual novel.
Here are a couple of screenshots of the game:
No release date has been announced yet- but considering that the game has already been translated into English before, it will probably be out fairly soon.